You can create a new profile if you want a clean start. See "Creating a profile": *https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles Note that you may want to remove the old profile if you do not intend to keep access to personal data stored in this profile. *https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile